Camrelizumab in advanced or metastatic solid tumour patients with DNA mismatch repair deficient or microsatellite instability high: an open-label prospective pivotal trial

Purpose Patients with DNA mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) cancers are prone to response to programmed cell death-1 (PD-1) checkpoint inhibitors. Therefore, we explored the efficacy and safety of a PD-1 checkpoint inhibitor camrelizumab in advanced or metastatic solid tumour with dMMR/MSI-H. Methods Patients with dMMR/MSI-H advanced or metastatic solid tumours who had received at least one line of prior systemic chemotherapy were recruited. Camrelizumab was given intravenously 200 mg every 2-week treatment cycle. The primary endpoint was objective response rate according to Response Evaluation Criteria in Solid Tumours v1.1. Results Twelve patients were enrolled. As data cutoff, eight patients (66.7%, 95% CI 34.9-90.1) achieved objective response. Disease control rate reached 100% (95% CI 73.5-100). Progression-free survival rate at 12 months was 83.3% (95% CI 48.2-95.6), and overall survival rate at 12 months was 90% (95% CI 47.3-98.5). The most common treatment-related adverse events were reactive cutaneous capillary endothelial proliferation (100%), increased alanine aminotransferase (41.7%), and increased aspartate aminotransferase (41.7%). Conclusions Camrelizumab provided durable objective response and disease control in pre-treated patients with dMMR/MSI-H advanced or metastatic solid tumour, being a promising treatment option for these patients.